Strings are used for storing text.
A String variable contains a collection of characters surrounded by double quotes ( "" ):
StringString Length
A String in Java is actually an object, which means it contains methods that can perform certain operations on strings.
For example, you can find the length of a string with the length() method:
Example
String txt = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
System.out.println("The length of the txt string is: " + txt.length());More String Methods
There are many string methods available in Java.
For example
- The toUpperCase() method converts a string to upper case letters.
- The toLowerCase() method converts a string to lower case letters.
Example
String txt = "Hello World";
System.out.println(txt.toUpperCase()); // Outputs "HELLO WORLD"
System.out.println(txt.toLowerCase()); // Outputs "hello world"Finding a Character in a String
The indexOf() method returns the index (the position) of the first occurrence of a specified text in a string (including whitespace):
Example
String txt = "Please locate where 'locate' occurs!";
System.out.println(txt.indexOf("locate")); // Outputs 7Java counts positions from zero. 0 is the first position in a string, 1 is the second, 2 is the third ...
You can use the charAt() method to access a character at a specific position in a string:
Example
String txt = "Hello";
System.out.println(txt.charAt(0)); // H
System.out.println(txt.charAt(4)); // oComparing Strings
To compare two strings, you can use the equals() method:
Example
String txt1 = "Hello";
String txt2 = "Hello";
String txt3 = "Greetings";
String txt4 = "Great things";
System.out.println(txt1.equals(txt2)); // true
System.out.println(txt3.equals(txt4)); // falseRemoving Whitespace
The trim() method removes whitespace from the beginning and the end of a string:
Example
String txt = " Hello World ";
System.out.println("Before: [" + txt + "]");
System.out.println("After: [" + txt.trim() + "]");